This happens daily to me as well. Very annoying.

Got the XE75Pro too and I have quite an unsatisfactory experience with it. When it switches to 80, my phone's connection to it at a mere 10 meters away, mostly unobstructed, will get very poor. Not bad enough to my phone switch to 5G.but bad enough that any streaming I consume gets very slow.

And my smart devices stop responding properly.

Does this happen regardless of hardware version (i.e. different chipsets / firmware)?

I ask this based on the following observation: I originally ordered a 2-pack of XE75. I had it up and running for 4 days until I decided I needed a 3-pack, so I returned the first kit and got a new one with 3 units.

Plot twist: The 2-pack was hardware revision 2.0. The replacement 3-pack was the old hardware rev. 1.0.

Now, the 2-pack with 2.0 hardware ran very smoothly without glitches. It intelligently picked a good, non-congested channel (48), and never once in 4 days did I get the 160 > 80 autoswitch due to radar interference. The 3-pack with hardware 1.0 behaves very differently. I get the 160 > 80 switch 2-3 times a day, and the so-called AI always picks the worst, most congested channel (36) no matter how I try to reboot or use the network optimization to make it reconsider channel choices.

Please tell me this difference is just a coincidence and that I didn't trade down to a second rate iteration of XE75... not that it would be much comfort that they behave like this regardless of hardware version.

  @Diod I just had a look at mine (3 node version) and it looks like it's hw ver 1.0.  After the serial number it has EU/1.0.

  @IntrovertSins 

Just for  current context to my original message  i switched the TP XE75 3 pack for a Asus XT9 ( 3 units ) . Manually selected channels, 1 for 2.5Ghz , 48 for 5Ghz and 112 for the 5Ghz backhaul. Based in England UK. ( did a wifi channel scan to check which ones were least congested in my area) 

Have DFS turned off for 5Ghz but on for backhaul but 160Mhz turned on for both. Wireless speed test in the loft wifi node around 815Mbps on a 900Mbps line. Been working for the last 2 months no issues or drops.  Wifi link speed showing as 1815/1922 in windows. 

So can be impletmented by manufactorers to work better as wifi environment  differ alot between locations and regions you need some flexibility to ensure things work well for you.

Is there a way to tell whether the Deco is presently utilizing 80 or 160? I've received the message about down switching to 80 but wonder if the Deco has up switched back to 160

  @IntrovertSins 160 is checked in Settings and has been since I set it up. Wondering when I get the down switch message due to DFS strike how to tell whether the Deco has gone back to 160?

If its set to 160 then then thats fine. I was struggling with DFS strikes where i live , caused instability with the 2 wireless nodes access points.

It should go back revert back to 160 automatically after some time anyway. You would only notice the speed difference with 160 if you have a fast connection over 400mbps ( i have 900 )  i think.

New firmware on the XE75 did not fix the issue so changed for different product unfortunatly,  was very happy with the Deco M9 3 pack but on the faster connection was not getting the benefit.

Having used the XE75 3-pack (HW version 1.0) now for a couple of weeks, here's my subjective experience:

Once it latches on to 160 MHz successfully, it stays there pretty much indefinitely. At least as long as I don't, er, 'disturb the sanctity' of the system. By that I mean, if I disconnect a node because I need to move it or whatever, or if I reboot the whole system, it has occasionally rubbed it the wrong way and thrown it into the old "switched temporarily to 80 MHz because...". And once this happens there is no way on earth I can get it to switch back. It insists that switching to 160 MHz is impossible, no matter how many dozens of times I ask it to reconsider, as if the neighborhood is hopelessly drenched in radar signals from all sides. But: If I reboot the whole setup, more often than not the supposed radar problem is suddenly gone and then it stays on 160 until the next time I ask for trouble by 'disturbing' the setup. This is odd, I mean either the radar is there or it's not, it can't magically disappear every time at the exact moment I trigger a reboot. It has to be a false positive blocking it from switching back without a reboot.